Taxpayers could stop subsidising onshore wind farms and solar power providers by the end of the decade, ministers claim.

Cabinet Office Minister Oliver Letwin has confirmed that financial support – currently worth around £400million – will have ‘disappeared’ by 2020.

George Osborne is believed to be arguing for a 25 per cent cut in renewable energy subsidies.

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But Mr Letwin revealed in an email to a campaigner that the cut could go much further.

‘I anticipate subsidies… will come
down to zero over the next few years and should have disappeared by
2020, since these forms of energy are gradually becoming economic
without the need for subsidies,’ he told Terry Stewart, president of the
Dorset branch of the Campaign for the Protection of Rural England.

The revelation is embarrassing for
Deputy Prime Minister Nick Clegg, due to attend the United Nations
Rio+20 Earth Summit in Brazil tomorrow.

The Lib Dem leader has argued national
wealth should also be measured by how clean a country’s environment is,
rather than just how much money it earns.

Ed Davey, the Liberal Democrat Energy
Secretary, will announce details of subsidies for renewable energy from
2013 to 2017 in the next few weeks.

It will follow a consultation on whether subsidies should be cut by more than 10 per cent.

John Constable, director of the UK
charity Renewable Energy Foundation, said: ‘Extremely high subsidies
have harmed the reputation and integrity of the renewables sector, which
has been corrupted by easy money and undeserved fortunes.

‘Reductions in subsidies are welcome,
but may not be enough to protect the consumer in very hard times, and
retrospective cuts, supported by windfall taxes, cannot be ruled out.’

A Department of Energy and Climate Change spokesman said the 2020 date referred to by Mr Letwin was an ‘aspiration’.

She added: ‘It is always our aspiration to end subsidies for any energies.’